Frequently asked Questions about High Efficiency Air Filters for Clean Room Junior High School (1)
1. What are the actual and nominal sizes of diaphragm-free hePA filters?
There is no high efficiency filter with clapboard why have actual size and nominal size, because nominal size is the filter that includes outside frame and filter material, and actual size generally gets rid of outside frame, only calculate the width, height, depth of filter material and the area of filter material.
2. Similarities and differences between high-efficiency filters with and without partitions?
The high efficiency filter can be divided into: high efficiency with and without partition.
The high efficiency filter with partition is made of superfine glass fiber as filter material, glue paper, aluminum platinum as partition, and wood frame or aluminum alloy frame glue. It has the advantages of high filtration efficiency, low resistance and large air volume, and is widely used in various local purification equipment and clean workshop.
Clapboard hepa filter is made of ultrafine glass fiber as filter material and hot-melt glue as separator. It is assembled with various outer frames and has beautiful outer frames. Compared with clapboard hePA filter, it has the advantages of small volume, light weight, compact structure and reliable performance under the same air volume.
3. Standard fold number, fold height and formula conversion of filter materials with and without partitions?
The folding height of filter paper with baffles is generally about 30mm~34mm shorter than the height of nominal size, and the folding number is mainly determined by the tightness of baffle paper, filter paper and baffle paper assembly.
Baffle paper radian according to the standard calculation, generally 4mm, less than 4mm, there is a partition between the number of more, in addition to the loose assembly, the result is counterproductive, there is a partition between the number of less, and no baffle filter paper folding number, mainly by the folding height of the filter paper, and the density of filter paper decided.
4. What are the similarities and differences between PP HEPA and glass fiber HEPA?
The comparison table of "PP HEPA" and "glass fiber HEPA" is as follows:
Project PP HEPA glass fiber HEPA
No skin irritation
There is no fiber shedding and the fiber shedding has serious harm to human body
Good filtering effect
5. What are junior, middle, senior high, sub-high and hePA filters?
Primary filter is suitable for pre-filtration of air conditioning system, mainly used to filter dust particles above 5um. Primary filters are available in three styles (folding, plate, bag). The outer frame material is paper frame, aluminum frame, galvanized frame, filter material is non-woven cloth, nylon mesh, activated carbon filter material, metal mesh, etc..
The medium effect filter is widely used in the intermediate filtration of air conditioning system, mainly used to filter dust particles of 1um~5um, with the advantages of small resistance and large air volume. The medium effect filter has bag type and frame type, combination type and so on.
Rfilter is mainly divided into two kinds of clapboard and clapboard filter.
6. Classification and performance comparison of primary, medium and high efficiency filters?
Filters with a dust counting efficiency of 20% and less than 80% for particles with a particle size greater than 5.0um are called primary filters.
Filters with a dust counting efficiency of 20% and less than 70% for particles with a particle size greater than 1.0um are called median-effect filters.
Filters with an air dust counting efficiency of 99.99% or more for particles with a particle size greater than 0.3um are called hePA filters.
7. Function and principle of fan filter screen set FFU?
The FFU laminar air supply unit can be used in modular connection, which makes FFU widely used in clean room, clean table, clean production line, packaged clean room and laminar flow cover applications.
FFU is provided with an initial high efficiency two-stage filter screen. The fan inhales the air from the top of FFU and sends the clean air filtered by the primary and high efficiency filter at a speed of 0.45m/s+20% on the whole air outlet surface.
8. What is the efficient and integrated air supply outlet?
The shell of the high efficiency air supply outlet is made of high quality cold-bonded steel plate, the surface of which is electrostatic spray, including the high efficiency filter of the static pressure box and the loose flow plate. In the rebuilt or newly built grade clean room, it can be used as the terminal high efficiency filter device in the clean shed and other places, which has the advantages of less investment and simple construction.
The integrated air supply outlet filter is a closed structure, low shape, light weight shell, with a high efficiency filter in the middle.
It has optimal filtration performance and is connected to the air duct for use in clean rooms with laminar and non-laminar flow grades 100,000 to 10. Closed design to prevent internal voidage and side leakage. Strict air quality requirements for clean room.
Its low profile, light weight and disposable design make it suitable for use in hospital operating rooms, laboratories, pharmaceuticals, microelectronics, film and food processing plants.
9. Current mixing ratio and standard dosage of high-efficiency filter with and without partitions?
The sealant currently used is A, B, and polyurethane
The mixing ratio of A and B glue is 1:2, its sealing performance is better, but once the ratio is out of balance, it will cause serious consequences. For example, the glue does not dry, or is the glue bubble and so on phenomenon, causes the filter to scrap.
10. Standard diagonals and accepted deviations for primary, medium, sub-high and high efficiency filters?
The standard diagonals of primary, medium and hePA filters are the sum of the squares of the two right-angled sides, and then the square root: to find the standard size of the diagonal line, namely the standard diagonal.
For filters greater than 700mm, the diagonal allowable deviation is less than or equal to 4.5mm, and for filters less than or equal to 700mm, the diagonal allowable deviation is less than or equal to 2.3mm.
11, what is the resistance, initial resistance, final resistance?
Resistance: Fibers cause airflow to detour, creating minimal resistance. The sum of the resistance of the countless fibers is the resistance of the filter.
Initial resistance: The air resistance of the tested filter without dust as it passes through the rated air volume.
Final resistance: refers to the initial resistance rising to the specified value due to the accumulation of dust in the filter under the rated air capacity, which is generally 2 times of the initial resistance. It can also be recommended by the manufacturer, and the unit is expressed in Pa.
12. Atmospheric dust, artificial dust and the proportion of artificial dust?
Atmospheric dust refers to the suspended particles contained in outdoor or indoor natural air connected with outdoor, while artificial dust is mainly composed of road dust, carbon black, and short velour, and its composition proportion is respectively 72%, 25%, 3%, etc..
13. What are the subject filter and end filter?
A filter that performs a standard performance test is called a subject filter.
The end filter is the filter used to trap artificial dust from the filter under test.
14. What is the rated air capacity? What is dust tolerance?
The processing air volume designed by the filter manufacturer in unit time is expressed in m3/h, and the dust capacity refers to the product of the total artificial dust mass exerted by the tested filter when it reaches the final resistance and the average weighing efficiency of the tested filter, and the unit is expressed as "g".
15. Standard fold number of hePA filters with partitions, and the factors that influence and determine their fold number?
The standard fold number of hePA filter with baffle is determined by two important factors such as the height of baffle paper and the tightness of baffle paper and filter paper during assembly.
For example, the standard fold of the filter of the wood frame (610*610*120) mm type is: first remove the thickness of the board on both sides, 610- (20*2) =570mm, its interval is 570÷4÷2=71.25 fold, the result is about 70~72 fold.
16. What is the frame and support body of the filter?
The frame of the filter is the object that holds the filter material, maintains the shape of the filter, and bears the external force.
The supporting body is the part that supports the filter material or keeps the air passage between the filter materials in a certain shape.
17. What is a clean room, cleanliness, and local space purification?
A clean room is a room or area where environmental control is required for particulate and microbial contamination.
cal space purification means that only the concentration of suspended particles in the specific local space of the indoor working area can reach the specified level of air cleanliness.
Cleanliness is defined as the allowable number of aerosols per unit volume of air in a clean environment that are greater than or equal to a particular particle.
18. What are the two test states of the filter? Test method for air filter and filter efficiency?
The test states of filters are: dynamic and static tests.
The test method of filter is: sodium flame method and oil mist method.
The test methods of filter efficiency include atmospheric dust test and artificial dust test.
19. What is the dust concentration? How to sample in the clean room (area) and how to arrange the sampling points evenly? How to determine the grade of clean room (area)?
The quantity or mass of suspended particles per unit volume of air.
When the unit is expressed as "granule/liter", it is called counting concentration; when the unit is expressed as mg/m3, it is called weighing concentration.
Sampling shall be conducted in a clean room and the sampling shall be uniformly arranged on a horizontal plane 0.8m above the ground level. When it is more than 5 o 'clock, it can also be arranged in the area with a height of 0.8m-1.5m from the ground. When sampling, determine the air supply and pressure difference, and avoid the return air outlet. The layout of sampling points in the clean room should be uniform to avoid the sparsity of sampling points in a local area.
20. What are the presentation principles and appearance requirements of the air filter's external dimensions?
The expression principle of the shape size of air filter is: take the direction of air flow through as the depth, take the vertical length of air flow through the direction of the correct installation of vertical length as the height, horizontal length as the width.
21. How to classify air filters according to their performance (type, filter material replacement)?
According to the type classification: flat type, folding type, bag type, winding type; According to the way of filter material replacement: cleaning, cleaning, disposable.
22. Principle and basis for the customer to judge whether the air filters (primary, medium and high efficiency filters) are qualified or not?
If a sample is drawn and one of the main items or two other items in the inspection item is unqualified, the sample is unqualified;
If one filter fails to pass the inspection when the sample is drawn, double drawing will be done. If one filter fails to pass the inspection, the batch of filters will be unqualified products.
If more than 3 filters (including 3 filters) all have the same defect, the whole batch of products will be disqualified.
23. What should be paid attention to in the process of labeling, packaging and transportation of air filters?
Label: Each filter must be marked in a prominent place and, if necessary, air flow direction, indicating at least the product name, filter model and specification, efficiency and initial resistance at rated air rate, name of manufacturer and date of production.
Packing: Packing shall ensure that the factory inspected filters are protected from external damage during loading, unloading, transportation, handling and storage until user installs them. The strainer shall be placed in a plastic bag before packaging and protected on both ends with a hard plate of the same size as the end face.
Transportation: during the transportation of the filter, the filter shall be placed according to the mark on the package, and fixed measures shall be taken to stack the filter at a height to avoid breakage.
24. Determination of grouping counting efficiency of atmospheric dust particle size?
Under the rated air volume, two dust particle counters are generally used to measure the particle count concentration of 0.5um or greater, 1.0um or equal, 3.0um or greater, and 5um or equal in the air above and below the test filter.
25. What are the conditions of temperature, humidity, and pressure plugs during cleanroom testing?
The temperature and relative humidity in the clean room area shall be appropriate to the requirements of the production process.
The temperature is controlled between 18°C and 24°C. Its relative humidity is 45%~ %. The pressure difference is generally relatively positive. The pressure difference between clean rooms with different air cleanliness should be less than or equal to 4.9Pa.